In recent years there has been a dramatic increase in the prevalence of antibiotic-resistant microorganisms. There is considerable concern in the medical community about penicillin resistant pneumococci, vancomycin resistant enterocci and methicillin and quinolone resistant Pseudomonas aeruginosa. Since the early 1980's in the United States and Europe, the incidence of infection by methicillin resistant Staphylococcus aureus (MRSA) and the vancomycin resistant enterococci (VRE) have increased substantially. In medical intensive care units around the country, increased colonization of vancomycin resistant enterococcus has recently reached epidemic proportions. These microorganisms survive by the colonization of the natural environment and new patients through cross contamination. Diarrhea and fecal incontinence further increase the risk of skin colonization by VRE, suggesting that skin colonization is associated with increased risk of catheter related sepsis, cross-infection, and blood culture contamination.
These findings suggest that in order to minimize VRE skin contamination the bacterial contamination of health care workers' hands must be reduced, thus interrupting transmission between patients.
Staphylococcus aureus is a major cause of nosocomial infections including: bloodstream infections, surgical site infections, and pneumonia. Summary data maintained by the Center for Disease Control demonstrated that from January 1990 through May 1999, Staphylococcus aureus infections accounted for: 12.6% of intensive care unit (ICU) acquired bloodstream infections, 18.1% of ICU acquired cases of pneumonia, and 16% of ICU acquired urinary tract infections. Surveillance reports indicate that further development of resistance by Staphylococcus aureus has increased rapidly in recent years and that the overall proportion of Staphylococcus aureus isolates resistant to methicillin in participating hospitals increased from 2.4% in 1975 to 29% in 1991.
Methicillin resistant Staphylococcus aureus (MRSA) infections have been associated with dialysis treatment, prior antibiotic use, hospitalization in a burn unit or intensive care unit, prolonged hospitalization, previous hospitalization, and previous invasive procedures. Reservoirs for MRSA are similar to reservoirs for other resistant staphylococcal strains. Environmental surfaces in rooms of MRSA patients, as well as patient care equipment are frequently contaminated. However, the role of MRSA transmission from such contamination has not been well studied.
Enterococcus is another problematic organism identified as a source of nosocomial infections. As with Staphylococcus aureus, there has been a substantial increase in the incidence of resistance to isolates of enterococcus bacteria. According to the CDC, the overall proportion of enterococcal isolates resistant to vancomycin in the ICU of participating hospitals increased by 40% in 1999 compared to the mean rate of resistance over the previous years from 1994 through 1998.
The pathogens isolated from infections differ, primarily depending upon the type of surgidal procedure. In clean surgical procedures, in which the gastrointestinal, gynecological, and respiratory tracts have not been entered, Staphylococcus aureus from the exogenous environment or the patient's skin flora is the usual source of infection. According to data from the National Nosocomial Infections Surveillance System, there has been little change in the incidence and distribution of the pathogens isolated from infections in the last decade. However, more of these pathogens show antimicrobial drug resistance, especially methicillin-resistant Staphylococcus aureus. 
Wound site infections are a major source of post-operative illness, accounting for many nosocomial infections. These infections number approximately 500,000 per year, among an estimated 27 million surgical procedures, infections that result in longer hospitalizations and higher costs. The average surgical site infection (SSI) prolongs the hospital stay by 7.3 days. These infections contribute to 42% of the extra charges attributed to nosocomial infections. In 1992, the extra costs were estimated at several thousand dollars per SSI infection.
On average, patients with surgical site infections incurred 4.6% extra ambulatory care visits than the patients who did not acquire these infections. In these hospitals, 0.62% to 1.9% of patients with surgical site infections died. These numbers highlight the tremendous human and financial costs that surgical site infections add to the healthcare system and therefore the importance of controlling them.
The antimicrobial effects of bisbiguanides have long been known. Chlorhexidine is the best known member of the class and has been used in the form of an aqueous solution or alcohol solution. Additionally, chlorhexidine has been marketed for many years in various formulas such as antibacterial hand washes and surgical scrub compositions for disinfection of hands and skin, disinfection of operation site, disinfection of medical instruments, disinfection of wounds, disinfection of operation room, patient's room, and the like. However, these formulations typically have included additional ingredients such as irritants, alcohols, and the like.
U.S. Pat. No. 6,107,261 to Taylor et al., issued Aug. 22, 2000, and its continuations-in-part, U.S. Pat. No. 6,204,230 to Taylor et al., issued Mar. 20, 2001 and U.S. Pat. No. 6,136,771 to Taylor et al., issued Oct. 24, 2000, disclose antibacterial compositions which contain an antibacterial agent at a percent saturation of at least 50%. The compositions further comprise, as solubility promoters, a surfactant and a hydric solvent, which may be an alcohol.
U.S. Pat. No. 5,776,430 to Osborne et al., issued Jul. 7, 1998, discloses a topical antimicrobial cleaner containing about 0.65-0.85% chlorhexidine and about 50-60% denatured alcohol, which is scrubbed onto and then rinsed off the skin.
European Patent Application 0604-848 discloses a gel comprising an antimicrobial agent, 40-90% by weight of an alcohol, and a polymer and thickening agent.
U.S. Pat. No. 4,956,170 to Lee, issued Sep. 11, 1990 relates to a high alcohol content antimicrobial gel composition which comprises various emollients and a humectant to protect the skin from the drying effects of the alcohol. In alcohol formulations, higher levels of alcohol are needed to provide instant kill against sensitive as well as resistant strains of bacteria.
U.S. Pat. No. 4,420,484 to Gorman et al. discloses a basic amino or ammonium antimicrobial agent (especially bisbiguanide, quaternary ammonium salt and bispyridine)-polyethylene glycol ester surfactant betaine and/or amine oxide surfactants antimicrobial skin cleansing compositions formulated with water, alcohol and various other ingredients.
U.S. Pat. No. 4,374,126 to Cardelli et al., teaches an alcoholic composition and method for forming a film where the composition comprises an alcohol soluble carboxylated polyacrylate which includes an antimicrobial agent, an adhesion promoter and a difunctional amide for crosslinking the polymer as the alcohol solvent evaporates. The film formed is thus resistant to body fluids, can remain on the skin for up to two days providing both initial and sustained anti-microbial activity.
U.S. Pat. Nos. 3,855,140 and 3,960,745 disclose the use of isopropyl alcohol while U.S. Pat. No. 4,919,837 discloses the use of lower alkanols such as ethanol or n-propanol. It is well known that alcohol defats the skin and may cause irritation thereof.
Cyclopentasiloxane (Velvesil™) is a silicone polymer that has been found useful in various cosmetic applications including antiperspirants, lotions, sunscreen, lipstick, shampoo, cuticle coat compositions, and hair conditioners, for example as disclosed in U.S. Pat. Nos. 6,444,745, issued Sep. 3, 2002; 6,531,540, issued Mar. 11, 2003; 6,538,061, issued Mar. 25, 2003; and 6,759,479, issued Jul. 6, 2004 all assigned to General Electric Company, Pittsfield, Mass. However, none of these patents disclose the use of cyclopentsiloxane as an ingredient in a non-alcoholic aqueous skin disinfectant for use as a surgical hand scrub, preoperative preparation, personnel hand wash, and the like.
Dyna-Hex 4®, a commercially available antimicrobial cleansing composition, manufactured and marketed by Xttrium Laboratories, consists of 4% chlorhexidine gluconate, cocamide DEA, fragrance POFL 147, glucono-delta-lactone, hydroxyethylcellulose, isopropyl alcohol, lauramine oxide, PEG-75 lanolin, purified water, and tridecyl alcohol. The isopropyl alcohol serves as a secondary vehicle for the other constituents.
There are two general problems associated with alcohol-based and/or containing disinfectants. First, the effective concentration of alcohol, generally regarded to be greater than about 60% weight of ethanol or its equivalent is irritating to the skin, causing dryness and consequent peeling and cracking. Due to the fact that chapped skin tends to be more susceptible to microbial contamination, repeated use of alcohol disinfectants can exacerbate the very problem they are intended to solve. Second, whereas alcohol can be an effective disinfectant, once it evaporates its antimicrobial activity is lost. Thus it has no residual antimicrobial effect.
Accordingly, a nonalcoholic antimicrobial cleansing composition which proves effective against Gram positive and Gram negative forms of bacteria and other microorganisms is highly desirable.
In recent years there has been an increased need and desire for effective antimicrobial products. The incidence of antimicrobial resistance has risen to dramatic levels. Yet at the same time there has been an increased need for products that are non-irritating and that can be applied quickly without the need for rinsing, i.e. a leave-on product.